Whenever my boyfriend and I have sex we are extremely careful, he uses a condom and I take birth control. ABout a month and a half ago I went to Scotland for 10 days and I had my period (late June 28th-July 2nd) when I was there and then a week and a half later (July 12th-16th) I had another period. My boyfriend and I had protected sex around July 20th and now I am four days late to my most recent period. I haven't taken a pregnancy test, but I was just wondering if stress could be what is affecting me OR if they two periods in one month could cause me to be late OR if the 2 weeks in Scotland and the different time zones, sleeping changes could be what's wrong.